The present invention relates to electric bicycles and in particular to controlling electric motor assistance to propelling the electric bicycle based on a rider's pedaling.
There is both a desire among consumers, and regulations requiring, that the electric motor power provided to the drive train of electric assisted bicycles be tied to the rider's manual power input via the pedals. That is, electric power is delivered to the drive train only if the rider manually rotates the pedals and then, such electric power must match or be some percentage of the actual power manually provided by the rider. Such electric bike systems are alternately referred to as Pedal Assist, PAS or Pedelec.
In order for such Pedal Assist systems to work, an accurate measurement of the power manually generated by the rider through the pedals must be made. Known systems for measuring the power provided by the rider are expensive to manufacture and there is a need for a power measuring device and method which is low cost with relation to the entire electric bicycle cost. Further, complex systems are often prone to failure and there is a need for a durable and low or zero maintenance system. Complex systems may further require calibration and adjustment and there is a need for a system which is easy to calibrate and adjust to obtain the desired accuracy.
Additionally, there is a need for a measurement device which can be fit onto existing bicycles with little or no modification to the existing vehicle thus allowing for a kit which can be attached by the consumer or manufacturer of existing bicycles.